Decomposition of the same component in the backround

Hello, I noticed a rather unfortunate behaviour:
Let’s say I have a component called shoulder. This is used in the glyph n. If I paste the glyph n into the backround of shoulder, that works fine, but if I decompose the components of n in the backround, the paths of the component shoulder that should appear after decomposition don’t show up. Only the stem of the n remains. Could this be fixed? Thanks!

Which version?

Same with the mekkablue script Decompose components in background?